Make stack potential more understandable

[pauloday]

Description of the problem being solved:

Change the note for stack potential to explain what it is, and display it as a percent instead of a float.

Move the note about using a weighted formula to the roll average breakdown, since that's where it's calculated. Also clarify when the weighted average is used.

Steps taken to verify a working solution:

• Ensure stack potential for ignite/bleed/poison are 0.95%/9.09%/1.75% in provided build
• Ensure stack potential breakdown has "The percentage of your max stacks that are applied on average if you are attacking constantly" as the only line at the top in green text
• Ensure average roll breakdown has "Uses weighted average formula when stack potential is over 100%" as the second green line

Link to a build that showcases this PR:

https://maxroll.gg/poe2/pob/1kmu90yp

Before screenshot:

After screenshot: